A well known type of hermetically sealed rotary compressors for use in refrigeration systems includes a hermetically sealed casing containing a compressor comprising a cylindrical wall and a pair of opposed end walls or plates defining a compression chamber. A roller is eccentrically mounted within the chamber and a vane is slidably mounted in a vane slot extending radially outward from the chamber within the cylindrical wall. The inner radial edge of the vane engages the periphery of the roller to divide the chamber into a low pressure side and a high pressure side. The vane is biased against the periphery of the roller by a spring. In operation of the compressor, rotation of the roller draws gas refrigerant into the low pressure side of the chamber and discharges compressed gas refrigerant from the high pressure side of the chamber.
Currently employed springs have proven satisfactory when used with relatively small displacement compressors as the spring is required to move through only a relatively short distance as the vane moves between the top-dead-center and bottom-dead-center positions of the roller. However, in larger displacement (volume) compressors the vane must move through a larger stroke distance and the spring thus is flexed to a greater degree. This places greater stress on the spring material. To some extent this may be compensated for by use of heavier spring materials; however, that increases the spring pressure on the vane and may adversely effects the operation. In addition, additional spring material would increase the cost of each compressor.
A primary object of this invention is to provide a rotary compressor including an improved vane biasing arrangement which is inexpensive and provides the needed biasing force without undue stress on the spring.